Determination of pitch in twisted cylinders by electromagnetic scattering

Nilsson, Börje

doi:10.1016/j.wavemoti.2005.10.001

Cited by 3 publications

(10 citation statements)

References 21 publications

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“…Later this model will be used to determine the pitch of the twisted uniaxial material [12] inside the cylinder using an inverse scattering technique. For applications like remote determination of spiral grain under bark of trees or wooden logs it would be practical to collocate the transmitting and the receiving antenna, e.g., in the same part of an instrument.…”

Section: Preliminaries and The Impedance Modelmentioning

confidence: 99%

“…For applications like remote determination of spiral grain under bark of trees or wooden logs it would be practical to collocate the transmitting and the receiving antenna, e.g., in the same part of an instrument. Such a request makes the problem three dimensional increasing significantly the numerical complexity by an additional Fourier integral [11] in comparison with the two dimensional formulation [12].…”

Section: Preliminaries and The Impedance Modelmentioning

confidence: 99%

“…Here refers to the axial and to the circumferential direction of the cylinder. A twist of this material with the pitch results in a twisted uniaxial material [12]. The fibres form a spiral pattern on the surface of the cylinder.…”

Section: Preliminaries and The Impedance Modelmentioning

confidence: 99%

“…Intended primarily for applications on wood, Nilsson [12] developed a two-dimensional inverse scattering theory for a cylinder with constant twist. The dielectric properties were measured simultaneously making the method insensitive to variations in temperature and humidity.…”

Section: Introductionmentioning

confidence: 99%

“…They review, in addition to microwaves, the use of ultrasonics, laser and visible light, infrared light, ionizing radiation, nuclear magnetic resonance and neutron radiography. Further references are given in [12], [13].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Estimation of Twist in Uniaxial Cylinders With Inverse Electromagnetic Scattering

Nilsson

Nordebo

Sojden

2009

IEEE Trans. Antennas Propagat.

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For the purpose of determining the twist of a homogeneous, locally reacting, uniaxial cylinder, an inverse microwave scattering theory is presented. Remote measurements of the spiral grain of trees and logs are the prime application. Based on practical considerations, it is assumed that the transmitting and receiving antennas are collocated, requiring a three-dimensional modelling. A general theory is first developed, followed by an asymptotic analysis assuming that the distance from the antennas to the cylinder is many wavelengths and many cylinder radii. In this way, a substantial reduction of the numerical complexity, to the level of the two-dimensional case, is achieved. The error of the determined twist angle as function of inherent parameters of the problem using a Cramér-Rao analysis is given. The results from numerical simulations show that this error is low enough for determining the grain angle. Presented parameter studies of the error can be used for minimizing the errors in a measurement set up, of particular interest for non-sophisticated instruments and non-ideal laboratory conditions, by selecting optimum parameters such as frequency and antenna gain. Finally, it is stated that the model has a great potential for developing efficient algorithms for measuring the twist angle.

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Section: Preliminaries and The Impedance Modelmentioning

confidence: 99%

Section: Preliminaries and The Impedance Modelmentioning

confidence: 99%

Section: Preliminaries and The Impedance Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Estimation of Twist in Uniaxial Cylinders With Inverse Electromagnetic Scattering

Nilsson

Nordebo

Sojden

2009

IEEE Trans. Antennas Propagat.

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A method for under-bark detection of the wood grain angle radial dependence

Nilsson

Sjödén

Nordebo

et al. 2007

Wood Material Science & Engineering

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Fisher information analysis for two-dimensional microwave tomography

2007

Self Cite

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In this paper, a Fisher information analysis is employed to establish some important physical performance bounds in microwave tomography. As a canonical problem, the two-dimensional electromagnetic inverse problem of imaging a cylinder with isotropic dielectric losses is considered. A fixed resolution is analysed by introducing a finite basis, i.e., pixels representing the material properties. The corresponding Cramér–Rao bound for estimating the pixel values is computed based on a calculation of the sensitivity field which is obtained by differentiating the observed field with respect to the estimated parameter. An optimum trade-off between the accuracy and the resolution is defined based on the Cramér–Rao bound, and its application to assess a practical resolution limit in the inverse problem is discussed. Numerical examples are included to illustrate how the Fisher information analysis can be used to investigate the significance of measurement distance, operating frequency and losses in the canonical tomography set-up.

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Determination of pitch in twisted cylinders by electromagnetic scattering

Cited by 3 publications

References 21 publications

Estimation of Twist in Uniaxial Cylinders With Inverse Electromagnetic Scattering

Estimation of Twist in Uniaxial Cylinders With Inverse Electromagnetic Scattering

A method for under-bark detection of the wood grain angle radial dependence

Fisher information analysis for two-dimensional microwave tomography

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